# if语句
age = 20
if age >  18:
    print('your age is', age)
    print('adult')

print('*'.join(['-' for i in range(20)]))
# if else 语句
age = 3
if age >= 18:
    print('your age is', age)
    print('adult')
else:
    print('your age is', age)
    print('teenager')

print('*'.join(['-' for i in range(20)]))
# if elif 语句
age = 3
if age >= 18:
    print('adult')
elif age >= 6:
    print('teenager')
else:
    print('kid')


print('*'.join(['-' for i in range(20)]))
# if 语句执行有个特点，它是从上往下判断，如果在某个判断上是 True, 把该判断对应的语句执行后，就忽略掉剩下的 elif 和 else, 所以，请测试并解释为什么下面的程序打印的是 teenager:
age = 20
if age >= 6:
    print('teenager')
elif age >= 18:
    print('adult')
else:
    print('kid')
# 输出结果是：teenager, 原因是第一个if就满足条件True，所以后面的语句就不再执行了